Single-loop polarization stabilization for single-mode fiber

A simple active control system is described that maintains the output of a single-mode fiber at prescribed polarization and intensity, thus counteracting erratic birefringeance effects in the fiber that are due to temperature drift and mechanical disturbances. Whereas the system of Ulrich [Appl. Phys. Lett. 35, 840 (1979)] controls two polarization parameters by means of two interdependent control loops, ours controls only one parameter and requires only a single control loop. The resulting considerable reduction of optical and electronic system complexity is realized at the expense of about 30-50% of input light intensity.